Medical Officer of Health Dr Phil Shoemack said the concern was that Zika virus has spread to countries such Brazil, which had not previously reported cases.

"Our concern is that recent research by the World Health Organisation confirms that when a woman contracts the Zika virus infection during pregnancy, there is risk it can cause birth defects in the baby."

There has also been three reported cases of Dengue fever this year, again involving people who had returned from overseas trips, he said.

The symptoms of Dengue Fever are similar to the Zika virus.

Dr Shoemack urges travelers to seek medical help if feeling unwell with 10 days of their return from an overseas trip.

An anyone was considering travelling overseas was urged to go online and check out the Ministry of Foreign Affairs' SafeTravel advice at www.safetravel.govt.nz/Travel Safe advice.